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    <title>Document</title>
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  <body>
    <script>

        // map 方法
    //   Array.prototype.myMap = function (fn) {
    //     let arr = [];
    //     for (let i = 0; i < this.length; i++) {
    //       arr.push(fn(this[i]));
    //       fn(this[i], i, this);
    //     }
    //     return arr;
    //   };

    //   const arr = [1, 2, 3, 4, 5, 6];

    //   const res = arr.myMap((item, index, array) => item + 1);

    //   console.log(res);


    //   filter

    Array.prototype.myFilter = function (fn){
        let arr = []
        for(let i= 0;i < this.length; i++){
            fn(this[i],i,this)
            if(fn(this[i])){
                arr.push(this[i])
            }
        }
        
        
        return arr

    }

    const arr = [1,2,3,4,5,6]


    // arr.myFilter()
    const res = arr.myFilter(item => item > 4)

    console.log(res);




    </script>
  </body>
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